The invention relates to an aiming device in combination with a device for guiding tracer missiles to the target, especially anti-tank missiles.
More particularly the invention relates to a combination of such an aiming and guiding device which uses the infrared beams of the spectral region.
In the combination the guiding device usually comprises first a goniometer for measuring the difference between the flight path of the missile and the line of sight of the aiming device and, secondly, a controlling device for transmitting control signals to the missile. The magnitude or intensity of the signals is derived from the measurement of the goniometer.
For fighting tanks, preferably semi-automatic weapon systems of the `line-of-sight-guiding-type` are used today. In this system, after firing the missile, the latter is caused to `jump` on the line of sight of the aiming device by signals transmitted by the controlling device which operates in combination with the aiming device. For such a guiding action it is a condition that the line of sight of the aiming device and the zero-line of the goniometer are identical or, at least, extend in parallel.
In such devices the goniometers use almost exclusively beams of a wave length of 0.002-0.005 millimeters (=2-5 .mu.m) which equals approximately 0.00008-0.0002 inches. In infrared technology this wave length region is known as the `1st window` as compared, for example, to the 3rd window which consists of beams having a wave length of approximately 8-14 .mu.m (=0.00032-0.00056 inches). The aiming device is usually a monocular telescope having cross lines. This constitutes a daylight aiming device.
For the use at night a supplementary aiming device is required which either works with infrared beams of the 1st window or of the 3rd window. Using beams of the 3rd window requires considerably more provisions especially with regard to the detector than would be needed if beams of the 1st window were applied. However, if beams of the 3rd window are used an image of the target is obtained that comprises considerably more information details than an image made up of beams of the 1st window.
Therefore, in spite of the more difficult working conditions mostly a night aiming device is used which works with beams of the 3rd window.
For the guiding device image details are not required.
Therefore the guiding devices usually work with infrared beams of the 1st window because this is easier to accomplish and less costly.
It is, however, a disadvantage of such a combined aiming and guiding device of which the aiming device works in the 3rd window and the guiding device works in the 1st window that in hazy weather in spite of poor visibility in the target area the aiming device still works satisfactory in the 10 .mu.m band while the guiding device in the 2 .mu.m band cannot see the missile, even at a short distance from the place of its firing. The guiding device can then no longer receive beams from the missile and conduct control signals to the missile and the missile may get lost.
It is therefore an object of the present invention to provide an infrared optical aiming and guiding device which overcomes this disadvantage.
This object could easily be attained if an aiming device and a guiding device would be combined that both use infrared beams of the same window. In such a combination the two devices will `see` the same objects, i.e. both will have the same range of vision. It can then no longer occur that the aiming device recognizes more details than the guiding device.
However, there arises the following difficulty: If the beams emitted by the missile and the beams used by the aiming device and the guiding device are of the same wavelength region then the missile light will blind the aiming device to an extent that makes proper aiming very difficult, if not completely impossible.
It is, therefore, the particular object of the invention to provide a combined infrared optical aiming and guiding device that both work in the same spectral region but wherein in spite thereof the aiming device is not blinded by the missile.